The present disclosure relates to stereoselective Ziegler-Natta catalyst compositions for use in polymerization reactions and propylene polymerization in particular.
It is known to incorporate a silane composition such as an alkoxysilane into a Ziegler-Natta catalyst system in order to improve selectivity and isotacticity control. Such selectivity control agents may further include an activity limiting agent such as an aromatic carboxylic acid ester to provide the catalyst system with a self-limiting property. However, it would be desirable to develop a self-limiting Ziegler-Natta catalyst system with improved catalyst activity and improved stereoselectivity that does not require an alkoxysilane.